1. Field of the Invention
An aspect of the present invention relates to a solar cell, and more particularly, to a solar cell having an improved electrode structure.
2. Description of the Related Art
A solar cell generates electrical energy from solar energy. The solar cell is environmentally friendly, and its energy source is endless. In addition, the solar cell has a long lifespan. Examples of the solar cell include a semiconductor solar cell and a dye-sensitized solar cell according to a scheme of how electrical energy is generated from solar energy.
In the semiconductor solar cell, a base and an emitter portion are formed in a semiconductor substrate, which have different types of conductivities, to form a p-n junction. A first electrode is electrically connected to the emitter portion, and a second electrode is electrically connected to the base.
Generally, the first electrode is formed on a front surface of the semiconductor substrate, and the second electrode is formed on a rear surface of the semiconductor substrate. However, if the first electrode is formed in a large area of the semiconductor substrate, in order to reduce resistance, the first electrode blocks the incident light on the front surface of the semiconductor substrate, thus increasing shading due to the increased size of the first electrode.
In order to reduce the shading, a solar cell in which the first electrode including a front portion formed on the front surface of the semiconductor substrate and a rear portion formed on the rear surface of the semiconductor substrate, and connected to the front portion through a via hole has been suggested.
In the above-structured solar cell, to reduce the shading, the width of the front portion of the first electrode should be small. However, if the width of the front surface is smaller than a predetermined width, a misalignment may arise by a process error in the forming of the front portion. If the misalignment exists, the area of the front portion contacting the via hole decreases, and the resistance increases and energy conversion efficiency is reduced. If the process error is extremely large, the front portion may not connect at all to the via hole, and thus the solar cell cannot work.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.